This model is discontinued
AirTAC has phased out the SI series. You can still order this code here: we ship the direct replacement SAI40X250SFA, with the same bore, stroke, output force, port and mounting, so it fits the same application. The SAI replacement keeps the same ISO 15552 mounting interface, bore, stroke, output force and accessories, so it drops straight into existing fixtures. It is the current-production version of this cylinder with an upgraded piston seal.
Airtac SI40 Standard Cylinder SI40X250SFA
The AirTAC Airtac SI40 Standard Cylinder SI40X250SFA is a double-acting ISO 15552 (orig. ISO 6431) profile-barrel cylinder with a Ø40mm bore and 250mm stroke, G1/4 air ports and adjustable end cushioning. This model is discontinued — the direct replacement is the SAI40X250SFA, which matches its ISO interface, bore, stroke, force and mounting.
- BoreØ40 mm
- Stroke250 mm
- Port sizeG1/4
- Acting typeDouble acting
- Rod threadM12×1.25
- StatusDiscontinued → SAI40X250SFA
- No minimum order. A single piece can be ordered.
- Ready in 3–5 business days. That is the time we take to process the order and hand it to the carrier. Transit time after that depends on the destination.
About the Airtac SI40 Standard Cylinder SI40X250SFA
The AirTAC SI40X250SFA is a discontinued double-acting ISO 15552 profile cylinder with a 40mm bore and 250mm stroke. Delivering 628 N push force at 0.5 MPa, it is replaced by the SAI40X250SFA. This direct upgrade keeps the same ISO 15552 mounting interface, G1/4 port, and FA flange. The SAI features an upgraded piston seal with two Y-shaped elements for low start-up pressure and long life.
The SAI family adds SAIL, SAIF, and BSAI variants absent in the SI line. Your SI40X250SFA includes a magnet for legacy CS1-B/DS1-B sensors, though the SAI uses current AirTAC switches. Rod material options include carbon steel, SUS420J2 (A), or SUS304 (B).
Airtac SI40 Standard Cylinder SI40X250SFA Technical Specifications
| Model | Airtac SI40 Standard Cylinder SI40X250SFA |
|---|---|
| Series | SI ISO 15552 profile cylinder (discontinued) |
| Replacement | SAI40X250SFA |
| Bore size | Ø40 mm |
| Stroke | 250 mm |
| Acting type | Double acting |
| Port size | G1/4 |
| Rod thread | M12×1.25 |
| Fluid | Air (filtered by 40µm element) |
|---|---|
| Operating pressure | 0.15 – 1.0 MPa |
| Proof pressure | 1.5 MPa |
| Temperature | -20 to +70 °C |
| Speed range | 30 – 800 mm/s |
| Cushion | Adjustable, 27 mm |
| Max standard stroke | Up to 1200 mm |
Specifications follow the official AirTAC SI datasheet (now discontinued). The SAI40X250SFA carries the same ISO 15552 ratings. Confirm against the product label before installation. Thread options: PT / G / NPT.
Theoretical Output Force (Ø40mm)
| Pressure | Push force | Pull force |
|---|---|---|
| 0.5 MPa | 628 N | 528 N |
| 0.7 MPa | 880 N | — |
| Max (@1.0 MPa) | 128 kgf | |
The SAI40X250SFA produces the same force from the same bore. Actual usable force is lower than theoretical; size with a margin.
Model Code: Airtac SI40 Standard Cylinder SI40X250SFA
| SI | ISO 15552 profile-barrel cylinder (discontinued). |
|---|---|
| 40 | Bore size in mm. |
| ×250 | Stroke length in mm. |
| -S | Optional built-in magnet for sensor position sensing. |
Legacy SI-family variants: SID (double rod), SIJ (adjustable stroke) — each maps to its SAI equivalent (SID→SAID, SIJ→SAIJ). Rod material: carbon steel (blank) / SUS420J2 (A) / SUS304 (B).
Where the Airtac SI40 Standard Cylinder SI40X250SFA Is Used
Clamp Actuation
Provides 628 N of clamping force at 0.5 MPa for securing mid-weight machining fixtures.
Package Diverting
Drives a 250mm stroke diverter arm to route boxes on automated packaging lines.
Replacing the Airtac SI40 Standard Cylinder SI40X250SFA with the SAI40X250SFA
To replace the SI40X250SFA, order the SAI40X250SFA. Verify the ISO 15552 FA flange interface, 40mm bore, 250mm stroke, G1/4 port (PT/G/NPT threads), and the magnet for position sensing. If you need more force, the neighboring 50mm bore yields 982 N push at 0.5 MPa; if less is acceptable, the 32mm bore provides 402 N. Because the 250mm stroke exceeds 300mm? No, at 250mm side-load risks are moderate, but always guide the load to prevent rod bending. A plain cylinder drifts on air loss—the cushion only decelerates. For load holding, use an external pilot check valve, rod lock, or the SAIL/BSAI lock variant.
Replacement checklist
- ✓ Same ISO 15552 interface → SAI40X250SFA
- ✓ Same bore / stroke / force
- ✓ Port/thread type (PT/G/NPT)
- ✓ Magnet (-S) for sensors?
- ✓ Mounting reused (FA/FB/CA/CB/CR/LB/TC)
Airtac SI40 Standard Cylinder SI40X250SFA FAQ
Yes, the AirTAC SI40X250SFA is discontinued. The direct replacement is the SAI40X250SFA. It is dimensionally interchangeable per ISO 15552, matching the 40mm bore, 250mm stroke, G1/4 port, FA flange, and output force.
The 40mm bore provides 628 N push and 528 N pull at 0.5 MPa, 879 N push at 0.7 MPa, and a theoretical max of 128 kgf at 1.0 MPa. Operating speed is 30-800 mm/s. It features a 16mm rod, M12x1.25 thread, and 27mm adjustable cushions.
Related AirTAC SAI Cylinders
Request a Quote for the SAI40X250SFA
Send us the quantity and destination. We confirm price, stock and lead time on the SAI40X250SFA replacement — usually within 7-8 hours.